USE OF TRICHOSANTHIN TO REDUCE INFECTION BY TURNIP MOSAIC-VIRUS

Exogenous application of recombinant trichosanthin (TCS) inhibited loc al lesion formation by turnip mosaic virus (TuMV) in leaves of Nicotia na tabacum and caused a delay in the development of mosaic symptoms by TuMV in Brassica parachinensis. A dose-response relationship was obse rved in the latter case. To produce transgenic plants expressing a TCS cDNA, a chimeric gene which contains a fusion between the cauliflower mosaic virus 35S promoter, the TCS-encoding cDNA and the octopine syn thase 3' polyadenylation sequence (ocs 3') was constructed. The chimer ic gene was then cloned into a binary vector and introduced into the g enome of N. tabacum cv. 'Wisconsin 38' via Agrobacterium tumefaciens-m ediated transformation. Three transgenic tobacco plants which synthesi zed TCS protein in the cytosol were completely resistant to mechanical inoculation of TuMV.